1. Field of the Invention
The present invention relates to a substrate having electronic elements formed thereon which can be utilized for controlling controlled elements and a method of manufacturing the electronic elements on the substrate. The present invention also relates to a substrate having electronic elements and controlled elements formed thereon, where the electronic elements can be operated to control the controlled elements, and a method of manufacturing the electronic elements and the controlled elements on the substrate.
2. Description of Related Art
Active matrix backplanes are widely used in flat panel displays for routing signals to pixels of the display to produce viewable pictures. Presently, active matrix backplanes for flat panel displays are formed by performing a series of processes. Exemplary processing steps to produce a poly-silicon active matrix backplane include the following steps:
Poly-silicon Backplane FabricationStepProcess 1Clean bottom glass 2Inspect 3Si Deposit 4Photoresist Coat 5Soft bake 6Expose 7Develop 8Hard Bake 9Etch10Strip11Anneal/dehydrogenate12Laser recrystalize13Insulator (SiO2) Deposit14SiNx Deposit15Gate Metal Deposit16Photoresist Coat17Soft Bake18Expose19Develop20Hard Bake21Etch22Strip23Anodize gate metal24Ion Doping25Dopant activation26Bus line metal deposit27Photoresist Coat28Expose29Soft Bake30Expose31Develop32Hard Bake33Etch34Strip35Deposit ITO36Photoresist Coat37Soft Bake38Expose Pixel Electrode39Develop40Hard Bake41Etch42Strip43Photoresist Coat44Soft Bake45Expose contact open46Develop47Hard Bake48Etch49Strip50SiNx Passivation Deposit51Photoresist Coat52Soft Bake53Expose contact open54Develop55Hard Bake56Etch57Strip58Interconnect metal deposit59Photoresist Coat60Soft Bake61Expose metal62Develop63Hard Bake64Etch65Strip
As can be seen, the poly-silicon active matrix backplane fabrication process includes numerous deposition and etching steps in order to define appropriate patterns of the backplane.
Because of the number of steps required to form a poly-silicon active matrix backplane, foundries of adequate capacity for volume production of poly-silicon backplanes are very expensive. The following is a partial list of exemplary equipment needed for manufacturing poly-silicon active matrix backplanes.
EquipmentGlass-handlingWet/dry stripGlass cleaningWet cleanPlasma CVDLaser CrystallizationSputteringIon ImplantResist CoaterResist strippingDeveloperParticle inspectionExposure systemsArray filet/repairDry etch systemAnti-ESD equipmentWet etch systemClean oven
Because of the nature of the poly-silicon active matrix backplane fabrication process, the foregoing equipment must be utilized in a class one (1) or class ten (10) clean room. In addition, because of the amount of equipment needed and the size of each piece of equipment the clean room must have a relatively large area which can be relatively expensive.
Moreover, poly-silicon is reproduced by recrystallization of amorphous silicon. This results in non-uniform grain size and carrier mobility, which then also translates into poor control of thin film transistor threshold voltages, particularly in large size circuits. These factors have so far limited the use of poly-silicon to small area backplanes used in LCD projectors.
It is, therefore, an object of the present invention to overcome the above limitations and others by providing an electronic device that includes a substrate having electronic elements formed thereon, which can be utilized for controlling controlled elements wherein the process of forming the electronic elements on the substrate is less complicated and less expensive than the process of forming electronic elements on backplanes using the poly-silicon active matrix backplane fabrication process described above. Still other objects will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.